Flutter Swift plugins seems incompatible with most of Flutter plugins #25676

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1. Sh1d0w commented on Dec 22, 2018

   

   Sh1d0w

   on Dec 22, 2018

   Last edited by Sh1d0w

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   As the creator of multi_image_picker plugin I would like to say I feel the same way. There are a lot of tickets in my repo, regarding developers struggling to use the plugin, simply because they haven't created their project with Swift template flag, thus missing !use_frameworks in their Pods file.

   Cocoapods 1.5 suggests that this flag should not be mandatory anymore when writing Swift code and including it in Objective-C project, but if you don't include it in the Flutter project the build fails with errors similar that the OP pointed out.

   As I am not an iOS developer, I would like to follow this topic to find a better approach to this, keeping the Swift code and providing the best experience for the developers, who want to use the plugin in the same time.

   FYI the firebase plugins should not require removing !use_frameworks anymore according to #25172 , but the problem with creating new flutter project without Swift flag (and so missing !use_frameworks by default) still exists when you try to add Swift plugins. All projects should have this flag by default, or we need to find why the build fails when it is missing.

   The other pain point is the Bridging Header. For projects created without the Swift flag, it is missing, and then I have to explain how to create that before using the Swift plugin.

   For me using plugins, either created by Swift or Objective-C should not require the developer to dig into native code in order to use the plugin, in a perfect world they would just install the package from the PUB and use it straight away. At least this is my experience with other cross platform frameworks I've used before Flutter.

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2. zoechi

   added

   toolAffects the "flutter" command-line tool. See also t: labels.Affects the "flutter" command-line tool. See also t: labels.

   p: toolingAffects the flutter_plugin_tools packageAffects the flutter_plugin_tools package

   plugin

   on Dec 22, 2018
3. zoechi

   added this to the GoalsThis milestone has been deleted milestone on Dec 22, 2018
4. FrenchTastic commented on Dec 22, 2018

   

   FrenchTastic

   on Dec 22, 2018

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   Thanks Sh1d0w for pointing me out that commented the tag is no longer required.

   But my understanding of the #25172 is that like the new project template commented this line by default (like this comment said) the step 4 of the plugin firebase_messaging is no longer required (because line is already commented).

   I totally agree with what you say and i'm still a little bit confuse about that's need to be done.

   Like you said we as "Flutter developer" should not to worry if the plugin that we are gonna use is written in Swift or Objective-C.
5. Sh1d0w commented on Dec 23, 2018

   

   Sh1d0w

   on Dec 23, 2018

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   @FrenchTastic Ah, you are right, I've must misinterpreted the issue I've linked, so the problem is still in place.

   Would be nice to hear some opinions from the Google team on this.
6. zoechi commented on Jan 8, 2019

   

   zoechi

   on Jan 8, 2019

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   #16049 seems related
7. zoechi

   added

   platform-iosiOS applications specificallyiOS applications specifically

   on Jan 8, 2019
8. amirh

   modified the milestones: GoalsThis milestone has been deleted, Near-term GoalsThis milestone has been deleted on Jan 10, 2019
9. dvaldivia commented on Jan 26, 2019

   

   dvaldivia

   on Jan 26, 2019

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   I have a problem with my project, most plugins have Objective-C code for iOS but trying to add plugins that use swift like flutter_photokit causes a build problem.

   Is it a safe assumtion that a work around would be to rebuild my whole project with the swift flag?

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10. collinjackson

    self-assigned this

    on Jan 31, 2019
11. dingjianjaja commented on Jul 4, 2019

    

    dingjianjaja

    on Jul 4, 2019

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    The easiest way to solve this problem is to create a new. swift file under the iOS file.

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12. jmagman commented on Sep 18, 2019

    

    jmagman

    on Sep 18, 2019

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    I was testing Swift plugins for add-to-app with both use_frameworks! (dynamic and static frameworks) and without (static libraries). I tested with flutter_photokit, CocoaPods 1.7.5 and Xcode 11 Seed 1.

    As-is, only the existing Swift app succeeded when use_frameworks! was present. Without use_frameworks! I saw 'flutter_photokit/flutter_photokit-Swift.h' file not found. And the Objective-C host couldn't get past pod install:

    [!] Unable to determine Swift version for the following pods:
    
    - `flutter_photokit` does not specify a Swift version and none of the targets (`ScaryBugs`) integrating it have the `SWIFT_VERSION` attribute set. Please contact the author or set the `SWIFT_VERSION` attribute in at least one of the targets that integrate this pod.

    	use_frameworks!	no use_frameworks!
    Obj-C host	[!] Unable to determine Swift version for the following pods:	[!] Unable to determine Swift version for the following pods:
    Swift host	✅	'flutter_photokit/flutter_photokit-Swift.h' file not found

    Then I tried adding s.swift_versions = ['4.0', '4.2', '5.0'] to the flutter_photokit.podspec. Now the Objective-C host builds.

    	use_frameworks!	no use_frameworks!
    Obj-C host	✅	✅
    Swift host	✅	'flutter_photokit/flutter_photokit-Swift.h' file not found

    Then I tried this __has_include hack. CocoaPods/CocoaPods#7594 (comment)
    I updated https://github.com/kmorkos/flutter_photokit/blob/master/ios/Classes/FlutterPhotokitPlugin.m to:

    #import "FlutterPhotokitPlugin.h"
    #if __has_include("flutter_photokit-Swift.h")
    #import "flutter_photokit-Swift.h"
    #else
    #import <flutter_photokit/flutter_photokit-Swift.h>
    #endif
    
    @implementation FlutterPhotokitPlugin
    + (void)registerWithRegistrar:(NSObject<FlutterPluginRegistrar>*)registrar {
      [SwiftFlutterPhotokitPlugin registerWithRegistrar:registrar];
    }
    @end

    But that broke Objective-C and fixed Swift:

    Undefined symbol: protocol conformance descriptor for Swift.String : Swift.CVarArg in Foundation
    Undefined symbol: Darwin._convertDarwinBooleanToBool(Darwin.DarwinBoolean) -> Swift.Bool
    Undefined symbol: _swift_getWitnessTable
    Undefined symbol: protocol descriptor for Swift.CVarArg
    Undefined symbol: _swift_getExistentialTypeMetadata
    Undefined symbol: _swift_getForeignTypeMetadata
    Undefined symbol: _swift_projectBox
    etc
    

    	use_frameworks!	no use_frameworks!
    Obj-C host	✅	Undefined symbol: protocol conformance descriptor for Swift.String : Swift.CVarArg in Foundation
    Swift host	✅	✅

    I am running Xcode 11 and I found this note https://stackoverflow.com/a/57126566 and added "$(TOOLCHAIN_DIR)/usr/lib/swift-5.0/$(PLATFORM_NAME)" to my app target's LIBRARY_SEARCH_PATHS and that gets me down to two undefined symbols:

    Undefined symbol: __swift_FORCE_LOAD_$_swiftCompatibilityDynamicReplacements
    Undefined symbol: __swift_FORCE_LOAD_$_swiftCompatibility50
    

    And now I'm in the bowels of Swift: https://github.com/apple/swift/blob/master/lib/IRGen/GenDecl.cpp#L454

    So I added "$(TOOLCHAIN_DIR)/usr/lib/swift/$(PLATFORM_NAME)" to my app target's LIBRARY_SEARCH_PATHS.

    	use_frameworks!	no use_frameworks!
    Obj-C host	✅	✅
    Swift host	✅	✅

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13. jmagman commented on Oct 10, 2019

    

    jmagman

    on Oct 10, 2019

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    I can see two things to update in the Swift plugin templates, which may unfortunately require a migration for existing plugins:

    1. Edit the implementation import:
       TestSwiftPlugin.m

    #if __has_include(<test_swift_plugin/test_swift_plugin-Swift.h>)
    #import <test_swift_plugin/test_swift_plugin-Swift.h>
    #else
    #import "test_swift_plugin-Swift.h"
    #endif

    2. Add swift_versions to the podspec so Objective-C apps can pod install and avoid

    [!] Unable to determine Swift version for the following pods:
    

    I'm hoping the Pod::Validator::DEFAULT_SWIFT_VERSION trick makes it more future-proof when the SDKs 3+ year from now stop supporting Swift 5.1:

    Pod::Spec.new do |s|
      s.name = 'flutter_plugin'
    ...
      swift_versions = ['4.0', '4.2', '5.0', '5.1']
      swift_versions << Pod::Validator::DEFAULT_SWIFT_VERSION if Pod::Validator.const_defined? "DEFAULT_SWIFT_VERSION"
      s.swift_versions = swift_versions
    end
14. ened commented on Oct 21, 2019

    

    ened

    on Oct 21, 2019

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    @jmagman after following your steps, I ended up with

    This copy of libswiftCore.dylib requires an OS version prior to 12.2.0.
    2019-10-21 09:29:46.179124+0100 Runner[4609:1101773] This copy of libswiftCore.dylib requires an OS version prior to 12.2.0.
    

    once running the App on iOS 13.1.3.
    Following the instructions on SO fixed it.
15. jmagman commented on Nov 7, 2019

    

    jmagman

    on Nov 7, 2019

    Last edited by jmagman

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    @jmagman after following your steps, I ended up with

    This copy of libswiftCore.dylib requires an OS version prior to 12.2.0.
    2019-10-21 09:29:46.179124+0100 Runner[4609:1101773] This copy of libswiftCore.dylib requires an OS version prior to 12.2.0.
    

    once running the App on iOS 13.1.3.
    Following the instructions on SO fixed it.

    Bleh, you're right. I don't see a better way to do this than the /usr/lib/swift LD_RUNPATH_SEARCH_PATHS suggestion. And it's not like I can even make it conditional on the LD_RUNPATH_SEARCH_PATHS[sdk=iphoneos13*] since the error is specifying a particular OS version.

    Fortunately it doesn't emit a warning when if the directory isn't found (before Swift shipped in the OS), like the linker does.
16. jmagman commented on Nov 8, 2019

    

    jmagman

    on Nov 8, 2019

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    I'm using this issue to track the plugin-side of this work (podspec, imports).
    The Objective-C app work (LIBRARY_SEARCH_PATHS, LD_RUNPATH_SEARCH_PATHS) is being tracked with #16049.

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17. jmagman

    closed this as completedin #44324on Nov 9, 2019
18. preble

    added 2 commits that reference this issue on Nov 19, 2019

    Adjust import of swift bridging header

    ...

    8683151

    Adjust swift_versions usage

    ...

    5403cf0
19. Hixie

    unassigned

    collinjackson

    on Aug 17, 2020
20. joecks commented on Apr 12, 2021

    

    joecks

    on Apr 12, 2021

    Last edited by joecks

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    Just FYI for whomever tries to extend a existing flutter pod (like in my case the webview_flutter ) with XCode 12.4:

    podspec:

      s.swift_version = '5.0'
      s.xcconfig = {
         'LIBRARY_SEARCH_PATHS' => '$(TOOLCHAIN_DIR)/usr/lib/swift/$(PLATFORM_NAME)/ $(SDKROOT)/usr/lib/swift',
         'LD_RUNPATH_SEARCH_PATHS' => '/usr/lib/swift',
    
         }

    2. Create empty Classes/webview_flutter-Bridging-Header.h
    3. run pod install
    4. Sample valid swift file

    import Foundation
    
    @objc public class HelloWorld : NSObject {
        @objc static public func hello() {
            print("hello world")
        }
    }

    6. Import auto-generated (run build once) header to .m file:

    #import <webview_flutter-Swift.h>
    ...
    
    // Hello World
    [HelloWorld hello];
    
21. github-actions commented on Aug 3, 2021

    

    github-actionsbot

    on Aug 3, 2021

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    This thread has been automatically locked since there has not been any recent activity after it was closed. If you are still experiencing a similar issue, please open a new bug, including the output of flutter doctor -v and a minimal reproduction of the issue.
22. github-actions

    locked as resolved and limited conversation to collaborators on Aug 3, 2021
23. flutter-triage-bot

    added

    packageflutter/packages repository. See also p: labels.flutter/packages repository. See also p: labels.

    on Jul 5, 2023